Semiconductor devices or integrated circuits (ICs) can include millions of devices, such as, transistors. Ultra-large scale integrated (ULSI) circuits can include complementary metal oxide semiconductor (CMOS) field effect transistors (FET). Despite the ability of conventional systems and processes to fabricate millions of devices on an IC, there is still a need to decrease the size of IC device features, and, thus, increase the number of devices on an IC.
One limitation to the smallness of IC critical dimensions is conventional lithography. In general, projection lithography refers to processes for pattern transfer between various media. According to conventional projection lithography, a silicon slice, the wafer, is coated uniformly with a radiation-sensitive film or coating, the photoresist. An exposing source of radiation illuminates selected areas of the surface through an intervening master template, the mask or reticle, for a particular pattern. The radiation can be light, such as ultra-violet light, vacuum ultra-violet (VUV) light and deep ultraviolet light. The radiation can also be x-ray radiation, e-beam radiation, etc.
The traditional way to reduce critical dimensions is to rely on improvements to the lithographic process. Such improvements can be time consuming and expensive, often requiring expensive new equipment. Even if a lithographic improvement is possible, a lithographic CD shrink is often accompanied by a rise in defect densities.
According to one conventional non-lithographic CD shrink process, mask layers have been subject to spacer etching processes to shrink lithographic features. These spacer etching processes usually utilize spacer materials composed of oxide or nitride material. The spacer materials are typically deposited and etched around compatible material layers, such as, polysilicon gates or nitride/oxide hardmasks.
An anti-reflective coating (ARC) has been conventionally provided underneath the photoresist material or the hard mask to reduce reflectivity and thereby, reduce resist notching, lifting and variation of critical dimension of the obtained pattern. Generally, the ARC (organic or inorganic) layer is a relatively thin layer which is not used as a hard mask because it is too thin and does not allow thickness flexibility due to optical design parameters. Conventional spacer etching processes generally have not been used with organic ARC layers due to material incompatibility issues associated with oxide and nitride spacer processes.
Thus, there is a need to shrink CD features using non-conventional polymerizing etch techniques. Further, there is a need for a process of forming smaller CD dimension that etches an ARC layer step. Yet further, there is a need for an organic ARC process that reduces CD size by etching. Even further still, there is a need for an etch recipe that effectively reduces CD size of ARC features. Yet further still, there is a need to reduce the CD or final inspected critical dimension (FICD) of an organic polymer spacer material by using a polymerizing gas additive to an established organic ARC etch process.